Immobilization devices such as a cast, a splint, a brace (orthosis) and stiffening apparatuses are used to impart a desired position to a supported portion of the body or to immobilize the supported portion relative to other parts of the body. Traditionally, plaster casting materials have been used because they are very low cost. However, plaster casting materials are heavy and cannot be cleaned or easily removed. Recently, plaster casting materials have been replaced by synthetic casting materials which are lighter in weight and can be cleaned but have a rough exterior surface and are still relatively heavy and bulky.
This plaster material however shows some important disadvantages such as its weight, the development dust, the occurrence of sharp and hard edges, and the time required for its application. In addition, it is also often necessary that a cast or other immobilization device be removed for medical consultation or exercise by a therapist and then put back on the patient. The plaster material casts cannot be removed intact and put back on the patient.
Braces have been described which are made of a sheet material impregnated or coated with a curable resin. For instance, U.S. Pat. No. 6,595,938 discloses an orthopedic casting article. In one embodiment, the article comprises a flexible sheet material impregnated or coated with two different resins. The article may be in the form of an orthopedic casting tape or a protective pad comprising a fabric backing that is longitudinally impregnated or coated with two different curable resins, preferably water-curable resins. The orthopedic casts are made by providing a curable casting tape; initiating the cure of the casting tape, e.g., by exposing the casting tape to water; and allowing the casting tape to cure to form an orthopedic cast.
Also U.S. Pat. No. 6,100,206 discloses orthopedic casting article comprising a curable resin, e.g. a water curable resin, and a filler associated with the resin, e.g. fibrous materials.
Another example of an orthopedic cast is disclosed in U.S. Pat. No. 4,888,225, which is directed to a splint comprising a sheet formed of an open-celled foam sheet impregnated with a water curable resin. Upon activation of the resin impregnated foam sheet and molding the same around the body part, an orthopedic splint is formed.
However, a common drawback of the braces comprising a curable resin is that the curing process takes a considerably time, e.g. around 30 minutes or more, before an orthopedic cast, which functional enough to support the injury is obtained. Moreover, the curing process is irreversible and it is impossible to shape the cured cast or splint in another position. Therefore the cast or splint has to be changed, i.e. one need to apply again a new cast or splint, in different phases of the healing process of the injury. In addition, to supply the cast or splint a physician needs to wear gloves.
Another problem is that casting or splinting may be very difficult, especially when it is required to build casts having different angles, e.g. a 90° angle between the foot joint and low leg, since at the same time it is necessary to make sure that a good angle is obtained, that the lamination and pressure is optimal, that contours are followed, etc. Furthermore, a cast or splint like those present in the prior art, wherein the casting material consists of a water-curable resin, and/or currently used products such as synthetic casts and/or P.O.P. (Plaster of Paris), have a cure (setting) time that can take more than one hour. During all that time the chosen casting position needs to be maintained, otherwise the casting material can loose the wanted position and it might be required to start all over again. It is very difficult to keep a patient for 30 minutes or more to up to one hour or more to sit still when he/she is in pain, or when he/she is, like most children, scared.
Thermoplastic materials are now being used for forming casts and braces and other immobilization devices. These thermoplastic materials can be produced in extruded sheets which, when brought to a melt point (50° C. to 100° C.), can be molded and manipulated to conform to and shape around a body part, such as a limb, and then allowed to cool to hardness. These materials can also be reheated, brought back to their original shape and then remolded into a different shape. Compared to other casting materials, the thermoplastic materials provide many advantages including simplicity of use and ease of cleaning.
U.S. Pat. No. 6,093,161 describes a thermoplastic apparatus for immobilization or support of a body part of a human or animal. The apparatus is formed from a sheet of thermoplastic moldable material that is substantially rigid at ambient temperatures and pliable at higher temperatures. The apparatus consists of two elements, which are fastened to one another by means of a fastener for fastening. The fastener is directly attached to the thermoplastic material, so that the fastener allows the thermoplastic apparatus to be removed from and put back on the human or animal body part.
However, a problem associated with the above-mentioned braces made of thermoplastic material is that they lack flexibility, and do not allow the injured body part to undergo slight movements, e.g. swelling. In addition, differences in pressure in the brace (orthosis), e.g. due to movements of a patient carrying the brace or due to swelling of the body part, may induce deformations or distortions in the brace configuration and/or create pressure contacts on the body part. In addition, application of the above-mentioned type of braces on impaired limbs, arms or other body parts, involves the adjustment and fastening of the fasteners to a patient, which is a time-demanding process. Another problem associated with this type of braces is that they are relatively heavy.
It has been suggested to use cork-like material for manufacturing braces and the like. NL 1013907 for instance describes a splint made of a disposable material containing a cork-like material such as EVA (ethylene vinyl acetate). However, a problem associated with such material is that it is not breathable. This is an important disadvantage, since for improving wound heeling and for permitting better transpiration, it is highly recommended to use braces or the like which are capable of some oxygen/air diffusion. It has been shown in the art that braces that are not sufficiently breathable can cause skin irritation, skin maceration, or skin dryness.
Another problem with currently known braces made of softer materials, is that the braces may be or become too soft once applied on a body part, and lose sufficient hardness, such that such braces may easily bend or form folds or pressure contacts on the body part, which may cause injury or sub-optimal recovery of the injured limb or joint.
The present invention seeks to remedy at least some of the aforementioned problems and drawbacks of the currently available immobilization devices, and offers other advantages over the prior art. In particular, it is an aim of the present invention to provide an orthosis showing improved flexibility but of a sufficient hardness. It is also an aim of the invention to provide an orthosis, which is breathable and comfortable. It is also an aim to provide an orthosis that allows facilitated and faster application on an injured body part.